Field of the Invention
The present invention relates to a human monocyte growth factor for stimulating differentiation and proliferation of human peripheral blood monocyte, and a purification process for purifying the growth factor.
The hematopoietic progenitor cell is differentiated to be converted into cells having various functions. Such a cell is referred to as polyfunctional stem cell, and proliferation or differentiation thereof requires stimulation by specific proliferating factor or differentiating factor. It has been known in the art that the following four CSFs (colony stimulating factors) should be present for differentiating the hematopoietic progenitor cell to glanulocyte or macrophage. The first factor is a multi-CSF known as interleukin 3 (IL3) which promotes the proliferation of the granulocyte, macrophage and precursors thereof, and induces the differentiation of these cell linages. The second factor is granulocyte CSF (G-CSF) which promotes differantiation and/or proliferation of the granulocyte; the third factor is macrophage CSF (M-CSF) which differentiates and/or proliferates the macrophage; and the fourth factor is granulocyte-macrophage CSF (GM-CSF) which promotes proliferation of both of the granulocyte and macrophage cell lineages.
The structures and DNA sequence of these four CSF derived from mouse (mouse CSF) have already been clarified (Metcalf. S., Science, 229, 16, (1985); OKABE, Tetsuro et al., "IGAKU NO AYUMI" (Progress in Medicine), 135, 1037, (1985).) Most of the CSF derived from human being (human CSF) have functions and structures similar to those of mouse CSF. However, human M-CSF, which stimulates human macrophage has not yet been found. For example, the human M-CSF is homologous with the mouse-CSF and performs immunological cross reaction to exhibit a CSF activity to the mouse bone marrow cell. However, it does not exhibit CSF activity to the human bone marrow cell ("RINSHO KAGAKU" (Clinical Science), 22, 255, (1986); Dao. S. K. et al., Blood, 58, 630, (1981)).
On the other hand, although it had been commonly considered that the human peripheral blood monocytes were cells which did not divide or proliferate, the inventor found a humoral factor for proliferating and differentiating the human monocytes in a cultured medium in which lymphocytes stimulated by lectin were cultured. This study also shows that human peripheral blood monocytes can divide and/or proliferate. (Biochem. Biophys. Res. Commun., 125, 705-711, (1985)). The humoral factors found previously and reported by me in the reference as aforementioned are present in two fractions, respectively, each having a molecular weight of 25,000 and 60,000 in the conditioned medium of lymphocytes, and the activities thereof are partially absorbed by anti-M-CSF antibody or anti-GM-CSF. Accordingly, the soluble factors are present as a mixture of various soluble factors including M-CSF, GM-CSF and others, and the mechanisms thereof have not yet been made clear. However, it is estimated that the proliferation and differentiation of human monocytes are stimulated by the synergistic functions thereof.
Under such circumstances, I have found a novel proteinous factor which induces proliferation and differentiation of human peripheral blood monocytes in the conditioned medium of human cancer cell line, and succeeded to purify the same as a single substance. Further, the thus found human monocyte growth factor was isolated to investigate the physiological activity thereof to ascertain that it was a substance having a novel physiological activity which was different from those of the known CSF and .gamma.-interferon. The human monocyte growth factor is expected to be used for a medicament for promoting the defensive action or reaction of the living body, into which the monocyte is participated; and thus it might be provided for an applications to exert various functions, including defensive action against infectious diseases, enhancement of immunological activities and enhancement of immunity against cancers by macrophage.